The present invention relates to an improved side bearing for mounting on a railway car truck bolster that provides improved control to limit rock and roll characteristics of the railway car in service.
In a typical railway freight train, such as shown in FIG. 1, railway cars 212, 214 are connected end to end by couplers 216, 218. Couplers 216, 218 are each received in draft sills 220, 222 of each respective car along with cushioning or draft gear assemblies not shown. Draft sills 220, 222 are provided at the end of the railway car center sill, and include center plates that rest in center plate bowls of railway car trucks 226, 228.
As is better shown in FIG. 2, each typical car truck 226 includes a pair of side frames 230, 232 supported on axle-wheel sets 234, 236. Bolster 238 extends between and is supported on springs 240 mounted on side frames 230, 232. Bolster center plate 224 includes a central opening 242. Side bearing pads 260 are provided laterally to each side of the center plate 224 on bolster 238. Side frames 230, 232 comprise a top member 244, compression member 246, tension member 248, column 250, pedestal 254, pedestal roof 256, wheel axle bearings 258, and bearing adapter 262. Side bearings are commonly used on railroad car trucks. Such side bearings are typically located on the truck bolster such as on side bearing pads 260, but may be located elsewhere on the bolster.
Typical side bearing arrangements are designed to control hunting of the railroad car. As a railroad car travels along the railroad track, a yaw excess motion can be induced in the railroad car truck. As the truck yaws, part of the side bearing is made to slide across the underside of a wear plate bolted to the railroad car body bolster. The resulting friction produces an opposing torque that acts to prevent such yaw motion. Another purpose of railroad car truck side bearings is control or limit the rock or roll motion of the car body. Most prior side bearing designs limited vertical travel of the side bearings. The maximum vertical travel of side bearings is specified in the Association of American Railroad Standards.
Accordingly, it is an object of the present invention to provide an improved side bearing which will limit the vertical rock or roll motion of the railway freight car.
It is another object of the present invention to provide an improved side bearing which will provide improved control over the rock or roll motion of an empty railway freight car.